Spatial and temporal variations in soil respiration among different land cover types under wet and dry years in an urban park

Abstract

Soil respiration (R-s) determines land surface carbon balance; however, there have been few studies that measured R-s in heterogeneous urban landscapes. Here, we investigated the spatial and temporal variations in R-s in six land cover types (mixed forest, deciduous broadleaf forest, evergreen needleleaf forest, lawn, wetland, and bare land) in Seoul Forest Park, Republic of Korea, between March 2013 and September 2014, which included a wet (2013) and an extremely dry (2014) summer. Spatially, there was a three-fold difference (0.48-1.45 kgC m(-2)) in annual R-s among the six land cover types. The soil organic carbon stock at a depth of 0.1 m explained 72% of the spatial variation in the annual R-s across the land cover types. During the entire study period, the soil temperature explained 82-97% of the temporal variation in R-s among different land cover types. Comparing the two summers, the 2014 drought only resulted in a decrease in R-s in the lawn plots (25%), which was driven by a reduction in the leaf area index and the fine root density. The temperature sensitivity of R-s in 2014 (dry summer) compared to 2013 (wet summer) was significantly lower in mixed forest, deciduous broadleaf forest, and lawn, and did not change in evergreen needleleaf forest, wetland, or bare land. The differences in R-s in these drought responses highlight the importance of the careful selection of land cover type during park planning to better manage carbon cycles.